【摘要】 为了研究天山造山带的地球动力学,自1970年代以来,国内外在天山造山带开展了大量的深部探测工作,并取得了丰富的成果,本文对这些工作和成果进行了梳理和综述.已有研究结果表明:天山造山带的地壳厚度较大,但并无明显山根;地壳结构具有垂向分层和横向分块特征;壳幔界面不清晰,莫霍面在盆山接合部下方发生错断;壳内普遍发育低速异常体,地壳泊松比较高,暗示了地壳力学上的弱化作用;上地幔也存在波速异常体,低速异常可能与地幔热物质上涌有关,高速体可能是古老板块的岩石圈拆离碎片;莫霍面错断、Q值结构和波速异常特征可以用天山南北侧稳定地质块体往天山造山带之下俯冲来解释,这也得到高分辨率层析成像结果的支持;剪切波分裂结果暗示有相当厚的上地幔卷入了造山过程.上述资料表明天山造山带的变形和隆升是其南北侧稳定地质块体的构造挤压与壳—幔复杂耦合作用的共同结果.更多还原

【Abstract】 In order to study the geodynamics of the Tianshan orogenic belt(TOB),a large amount of works for probing the deep structure of the TOB have been conducted in this area since 1970s,and abundant achievements have been acquired.The purpose of this paper is to summarize these works and achievements.The study results show that: The crust of the TOB is relatively thicker and there is not a clear mountain root.The crustal structure is characterized by the vertically layering and the laterally blocking.The crust-mantle boundary is not clear and the Moho is dislocated beneath the basin-range junction zones.The low-velocity anomalies commonly existing in the crustal interior and the relatively higher crustal Possion’s ratio imply the mechanical weakness of the crust.Velocity anomalies also exist in the upper mantle,the low ones are likely to be related to the upwelling of the hot mantle materials and the high ones may be the lithospheric detachment fragments of the age-old plates.The dislocation of the Moho,the Q-value structure and the velocity anomalies can be interpreted by the underthrusting of the stable rigid geological blocks to the TOB from the south and the north,and this interpretion is also evidenced by the high-resolutional tomographic images.The shear wave splitting results imply that the upper mantle involved in the orogen movement is considerablely thick.The above knowledge suggests that the deformation and the uplift of the TOB are resulted from the combined actions of the tectonic compression of the southern and northern stable blocks and the complex crust-mantle coupling.更多还原